Green Analytical Chemistry

Mihkel Koel, Mihkel Kaljurand

• Publisher: Royal Society of Chemistry
• Year: 2019
• ISBN:
  9781788017565
• Edition: 2
• Topic: Physical Sciences
• Subtopic: Analytic Chemistry

Chemical analysis requires solvents, reagents and energy and generates waste. The main goal of green analytical chemistry is to avoid or reduce the undesirable environmental side effects of chemical analysis, while preserving the classic analytical parameters of accuracy, sensitivity, selectivity and precision.

This book portrays the current and changing situation concerning adoption of the principles of green chemistry as applied to analysis. It begins by looking at the advantages of and problems associated with on-site analysis and how analytical techniques can lead to increased productivity, efficiency and accuracy, and thereby reduce the consumption of materials. It then focuses on sample preparation techniques minimising solvent consumption or using alternative solvents, concepts and methods of improving the 'greenness' of instrumental analysis where miniaturization is an important part, separation methods from the perspective of green analytical chemistry and chemometrics approaches, which can reduce or can even remove the need for conventional steps in chemical analysis.

Aimed at graduates and novices just entering the field, managers of analytical research laboratories, teachers of analytical chemistry and green public policy makers, this title will be a useful addition to any analytical scientist's library.

1 Introduction to Green Chemistry

Science is the cornerstone of the development of human society. It provides humans with very powerful tools, which if used carelessly could endanger their world. It is conceivable that without serious effort, this scenario could prevail and the further development of society could be jeopardised.

Chemistry is a very old discipline, with references to chemical transformations and debate about the nature of matter dating back to the times of the ancient Egyptians and Greeks. Modern chemistry began to emerge from alchemy in the seventeenth and eighteenth centuries, thanks to scholars such as Robert Boyle and Antoine Lavoisier, and made rapid advances in the following two centuries. Understanding phenomena at the molecular level is vital to future innovation and invention in chemistry. The structure and bonding of molecules is at the core of the discipline, especially in organic chemistry.

The chemical sciences continue to be at the heart of multidisciplinary initiatives. Today, chemical tools—and the analytical tools chemists use—are especially pertinent to research in biology; even more, much of biotechnology is actually chemistry. The chemical sciences provide the wide expertise for most scientific and technological developments and thus continue to make enormous contributions to social, cultural, economic and intellectual advances. Chemistry contributes to our wellbeing, long life expectancy and economic prosperity. It satisfies the desire for better materials for everyday life and accommodation, for drugs to cure illnesses and improve health, and for pure water, and a host of other human needs.

However, environmental chemistry data are making it clear that the excessive use of natural resources has seriously affected our life-support system: Human society faces many dangers, such as environmental pollution, climate change, and the loss of biodiversity. These issues create major risks for ecosystems and are a serious threat to the sustainability of life on Earth. Anthropogenic pressure may continue to exacerbate present-day problems.¹ One obvious and extremely negative sign of human activity is the Pacific Gyre Garbage Patch – a gyre of marine debris in the central North Pacific Ocean. The Pacific Garbage Patch is the world's largest, but not only, area of marine debris concentration. The patch is located within the 23 million square kilometres of the North Pacific Subtropical Gyre, an enormous swirling expanse of ocean caused by the convergence of four major currents, which pull in trash from as far away as the coasts of the United States and Japan. This patch, which was first noticed in 1997, has high concentrations of pelagic plastics, chemical sludge, and other debris, and has been formed gradually as a result of marine pollution gathered by oceanic currents.²

There are other places on Earth where one can see the results of detrimental human activity, such as hypoxic (low-oxygen) areas in the world's oceans, large lakes and major river deltas. Runoff from farms has led to persistent “dead zones” at the base of rivers. The excessive algae blooms triggered by the quantity of nutrients in the runoff deplete the oxygen, resulting in the extermination of the algae as well as all other marine life within the zone. These nutrients come from all over the river basin, which is the drainage area for a substantial area of land. In the 1970s oceanographers began to note increased instances of dead zones.³

The prevention and mitigation of environmental damage requires sound science and dedicated political support. T. Collins raised a crucial question about our species: “Is a large technologically powerful human population sustainable on the earth?”.⁴ Physical needs such as nutrition, sanitation, access to electricity, and the elimination of extreme poverty could likely be met for everyone without transgressing planetary limits. However, the universal achievement of more qualitative goals (for example, high satisfaction with life) would require a level of resources that is 2–6 times the sustainable level, based on current calculations. Strategies to improve physical and social provisioning systems, with a focus on sufficiency and equity, have the potential to move nations towards sustainability, but the challenge remains substantial.⁵

For this reason, energy and sustainable chemistry are key themes in current discussions about the future. Chemicals are present in all spheres of human life: they are used as pharmaceuticals, pesticides, detergents, fertilisers, dyes, paints, preservatives, and food additives. The first and most influential description of the dangers related to chemicals in the environment is found in Rachel Carson's Silent Spring, published in 1962,⁶ and now is complemented additionally to chemicals from risk of corruption in science by Carey Gillam's Whitewash.⁷

Chemical spills and accidents range from minor to major, and can occur anywhere chemicals are found, from oil drilling rigs to factories, and fifty-five-gallon drums to tanker trucks, in every location from your garden tool shed to the local dry cleaner, and for a variety of reasons, from process and safety-control-system failures resulting from technical or human errors, to sabotage. The US National Environmental Law Center stated that 34 500 accidents involving toxic chemicals were reported to the EPA Emergency Response and Notification System between 1988 and 1992, indicating that, on average, a toxic chemical accident was reported nineteen times a day in the United States, or nearly once an hour.⁸ The impact of chemical accidents can be deadly, both for humans and the environment. One of the most common concerns related to chemical and hazardous material accidents is acute or short-term toxicity. Another result of chemical spills and accidents is ecotoxicity, a toxic effect on the environment. Transportation accidents, whether airplane, ship, train or car, can also have disastrous consequences, e.g., affecting a large number of passengers, spilling huge amounts of oil or chemicals, or causing a fire.

Environmental issues are a constant concern of the Organisation for Economic Co-operation and Development (OECD), an international body composed of more than 30 industrialised countries that has existed since the 1980s. The OECD has made a series of international recommendations that focus on co-operative change with regard to existing chemical processes and pollution prevention.^9,10

Synthetic chemicals enter the environment not only by accident. The chemical industry is a point source of emissions that cause changes around that point. In everyday life the constituents and ingredients of consumer or household products and other open applications emit chemicals into the environment from a myriad of sources. Chemicals and their compositions do degrade and break down into water, carbon dioxide and inorganic salts, but very often the degradation is incomplete. Unknown transformation products can result from biological and chemical processes such as hydrolysis, redox reactions and photolysis. These unknown chemical entities remain in the environment and can be toxic to humans and environmental organisms. The latter situation is more serious as there is usually much less knowledge about the longevity and effects on the environment of the final transformation products than there is about the parent compounds. Even if there is some degree of degradation, the parent compounds will nevertheless remain at constant levels in the environment if the input rate is higher than their rate of degradation or mineralisation. This situation has to do with persistency, which is one of the most important criteria in the environmental assessment of chemicals. Persistent organic pollutants (POPs) are a group of chemicals possessing the following characteristics:

• Highly toxic to humans and wildlife (harmfulness);
• Remain in the environment for many years before degrading into less dangerous forms (persistence);
• Accumulate in the food chain (bio-accumulation);
• Transported over large distances through air and water and can be found everywhere in the world (long-range transport).

POPs have been widely used in agriculture and industry, and they have been unintentionally produced and released from many anthropogenic activities around the globe. The effects of POPs on health include cancer, allergies and hypersensitivity, damage to the central and peripheral nervous systems, reproductive disorders, and disruption of the immune system.

In 1995 the Governing Council of the United Nations Environment Programme (UNEP) called for global action to assess the effects of POPs. The twelve worst offenders are known as the “dirty dozen” and include eight organo-chlorine pesticides – aldrin, chlordane, dichloro diphenyl trichloro ethane (DDT), dieldrin, endrin, heptachlor, mirex and toxaphene; two industrial chemicals – hexachlorobenzene (HCB) and the polychlorinated biphenyl (PCB) group; and two groups of industrial by-products – dioxins and furans.¹¹ It became clear that these POPs were deadly and that urgent global action was needed. Recent research has demonstrated that chemicals that are less persistent and have a higher polarity than PCBs are distributed globally as well, and can also accumulate in humans. In May 2001 the Stockholm Convention on Persistent Organic Pollutants was convened.¹² The Convention initially outlawed the dirty dozen and established a system to track additional substances that could be classified as POPs, in order to prevent the development of new problem chemicals. There are 26 POPs listed at present; however, the treaty is a living document and new POPs are regularly added to its annexes. Annex A lists chemicals for which signatories must take measures to eliminate production and use; Annex B lists chemicals for which signatories must take measures to restrict production and use; Annex C lists chemicals for which signatories must take measures to reduce unintentional release.

Polychlorinated biphenyls (PCBs) are a classic example of persistent pollutants. PCBs were synthesised for the first time in 1877, and as early as 1899 severe health problems (chloracne) were associated with handling them. Since then, the poisoning of rice oil by these compounds and their neurotoxic effects and carcinogenicity has been described in detail. Despite this knowledge, it was not until 1999 that PCBs were completely banned within the EU – 100 years after the first reports of their severe toxicity. This example clearly illustrates that it is not only the time lag in the impact of chemicals on environmental processes that has a significant effect, but also the time lag in economic and political systems.

Examples of pollutants with a much shorter history are the inert organohalogen compounds, known as Freons. They were initially developed in the early 20th century as an alternative to the toxic gases that were used as refrigerants, such as ammonia, chloromethane and sulfur dioxide. These Freon compounds, which contain only chlorine, fluorine, and carbon, are called chlorofluorocarbons (CFCs), and each is designated by a number. For instance, Freon-11 is trichlorofluoromethane and Freon-12 is dichlorodifluoromethane. The most common is Freon-113, trichlorotrifluoroethane, used as a cleaning agent.

In the 1970s, scientific evidence revealed that human-produced chemicals are responsible for observed depletions of the ozone layer. In 1978, the United States, Canada and Norway ...

Table of contents

• Cover
• Title
• Copyright
• Contents
• 1 Introduction to Green Chemistry
• 2 Concepts and Trends in Green Analytical Chemistry
• 3 Greening Sample Treatment
• 4 Green Instrumental Analysis
• 5 Separation Methods in Analytical Chemistry
• 6 Greening Analytical Chemistry by Chemometrics
• 7 Conclusions
• Subject Index